[vb.net] how to add new rows into a datatable vb.net

I have a form with a textbox and a "add" button.

1. The user can write a name down on the textbox and click the "add" button. It will save in a datatable with auto ID.
2. After that, the textbox is cleared and the user can write another name in the text box and click the button.
3. This should add to the existing datatable in memory with existing ID + 1.
4. Then show in the gridview. (this is just for display purpose to confirm it works)

I have a datatable like this.

    Button1.click() event

    Dim name = txtname.Text
    Dim dt As New DataTable
    dt.Columns.Add("ID", GetType(Integer))
    dt.Columns.Add("Name", GetType(String))
    Dim N As Integer = dt.Columns("ID").AutoIncrement
    dt.Rows.Add(N, name)
    GridView1.DataSource = dt
    GridView1.DataBind()
    txtname.Text = ""

At the moment I have sometime like the code above. in the real program, it is not just name and it is not just one datatable so i just mock up some code.

and this code for aspx.

        <asp:TextBox ID="txtname" runat="server">
        </asp:TextBox><asp:Button ID="Button1" runat="server" Text="Button" />
        <asp:GridView ID="GridView1" runat="server">
        </asp:GridView>

can anyone advice me how to do it ? i understand my code is crapped and not correct but i just have to put some code so that you guys not need to work from scratch for me.

Thanks so much.